1. Field of the Invention
The present invention relates, in general, to a radio wave transmission/reception device for vehicles and, more particularly, to a radio wave transmission/reception device for vehicles, which can increase the rectilinearity of propagation of radio waves, thus avoiding errors in distance measurement caused by noise and improving the appearance of vehicles.
2. Description of the Related Art
In recent years, a variety of Intelligent Driver Assistance Systems (IDAS) designed to provide safety and comfort to drivers, such as Car Navigation Systems (CNS), Lane Departure Warning Systems (LDWS), Sleepy Alarm Systems (SAS) and Collision Avoidance Systems (CAS), have been actively studied and developed.
The Intelligent Driver Assistance System (IDAS) typically uses a radio wave sensor to detect obstacles in front of a traveling vehicle. Particularly, a radio wave sensor transmits radio waves having a wavelength of 1-10 millimeters in a desired direction and receives radio waves reflected by an obstacle in front of a vehicle and determines the distance between the vehicle and the obstacle, so that the radio wave sensor can quickly detect and analyze the situation in front of the vehicle even when the situation is not within the field of vision of a driver, thus being preferably and widely used.
To secure the desired operational reliability of Adaptive Cruise Control Systems (ACCS), it is very important to provide a technique of accurately transmitting and receiving radio waves and determining the precise distance between the driver's car and the car facing immediately ahead. Thus, in the prior art, the development of techniques related to ACCS has focused on the improvement of the shapes and materials of a variety of devices, which may impede the transmission/reception of radio waves during the process of transmitting/receiving the radio waves.
An example of prior art techniques related to the present invention is a radio wave sensor disclosed in Japanese Patent Laid-open Publication No. 2004-312696. The radio wave sensor disclosed in No. 2004-312696 was proposed to solve the problem experienced in conventional techniques due to noise detected when radio waves having a wavelength of 1-10 millimeters are transmitted to materials around the sides of a vehicle and the waves reflected by the materials are received.
In the radio wave sensor, a radio wave transmission/reception antenna is installed such that it is oriented forwards relative to the vehicle. Further, in the radio wave sensor, a layer having a dielectric loss or a magnetic loss higher than that of the front surface of a radar cover is embedded in the side surface of the radar cover, or the side surface of the radar cover is made of a material having a relative dielectric constant higher than that of the front surface of the transmission/reception antenna.
However, the prior art radio wave sensor disclosed in Japanese Patent Laid-open Publication No. 2004-312696 is problematic in that, although the radio waves transmitted from the radio wave transmission/reception antenna are partially intercepted by the side surfaces of the radar cover, the radio waves do not propagate rectilinearly, but disperse while propagating forwards. Thus, when the dispersed radio waves are reflected backwards by obstacles and are received by the radio wave sensor, noise is undesirably received by the radio wave sensor along with the reflected radio waves.
Further, in the prior art technique, the transmission/reception antenna cover is made of a simple plastic material, so that, when the antenna cover is mounted on the front of a vehicle, it spoils the appearance of the vehicle.
Thus, in the related art, it is required to develop a radio wave transmission/reception device for vehicles that can prevent the dispersion of radio waves transmitted from and received by a radio wave sensor, thus reducing noise received along with the reflected radio waves by the radio wave sensor, and can determine the precise distance between a vehicle and an obstacle in front of the vehicle, and can improve the appearance of the vehicle.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.